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    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>
    <script>
        Array.prototype.max = function () {
            return Math.max(...this)
        }
        Array.prototype.min = function () {
            return Math.min(...this)
        }
        Array.prototype.sum = function () {
            let sum = 0;
            for (let i = 0; i < this.length; i++) {
                sum += arr[i]
            }
            return sum;
        }

        Array.prototype.avg = function () {
            let sum = 0;
            for (let i = 0; i < this.length; i++) {
                sum += arr[i]
            }
            return sum / this.length;
        }
        let arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
        console.log(arr.max())
        console.log(arr.min())
        console.log(arr.sum())
        console.log(arr.avg())
    </script>
</body>

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